Illuminating device, image reading apparatus and image forming apparatus

ABSTRACT

An illuminating device ( 210 ) according to an embodiment of the invention included in an image reading apparatus ( 100 ) and an image forming apparatus (D) includes light source portions ( 211   a   1 ), ( 211   b   1 ), ( 211   a   2 ) and ( 211   b   2 ), light-guiding members ( 213   a ) and ( 213   b ) for illuminating an illumination target (G) from an elongated light emitting face (M) that extends in a longitudinal direction (Y), by guiding light from the light source portions, and holding members ( 216   a ) and ( 216   b ) for holding the light-guiding members. The holding members include holding portions ( 2161   a ) and ( 2161   b ) for removably holding the light-guiding members, and tilted portions ( 2162   a ) and ( 2162   b ) that reflect light emitted from the light emitting face (M), the tilted portions extending from a front end on the light emitting face (M) side of the holding portions, obliquely widening with increasing distance from the light-guiding members.

TECHNICAL FIELD

The present invention relates to an illuminating device that illuminatesan illumination target, an image reading apparatus and an image formingapparatus.

BACKGROUND ART

Generally, in image reading apparatuses provided in image formingapparatuses such as a copier, fax machine or digital multi-functionalperipheral, or image reading apparatuses contacted to a computer viacommunication means such as a network, light reflected from a documentserving as the illumination target that is illuminated by anilluminating device including a light source for illuminating thedocument is read as the document image.

For example, a conventional image reading apparatus includes a lightsource unit in which an illuminating device including a light sourceportion (for example, a bar-shaped light source such as a halogen lampor xenon lamp, or a light source constituted by a light-emitting elementsuch as light-emitting diodes (LEDs)) for illuminating a document placedon a platen glass and a first mirror are arranged, second and thirdmirrors, an imaging lens and an imaging element (for example, a linesensor such as a CCD (Charge Coupled Device)). Many of such imagereading apparatuses are configured to read a document image by causingreflected light from the document illuminated by a light source portionto pass through a slit provided in a base such as a frame body of theilluminating device, and to travel via a first mirror, a second mirror,a third mirror and then an imaging lens to form an image on an imagingelement.

For example, such image reading apparatuses are used as image readingmeans in the case where information of the image formed on the imagingelement such as a CCD is converted to electric signals to be subjectedto image processing, and the processed electric signals are transferredto an image forming apparatus that performs printing based on the imageinformation, or in the case where the electric signals are sent to acomputer (for example, personal computer) connected to a network.

Conventionally, an illuminating device provided in an image readingapparatus is known which includes a light source portion, an elongatedand translucent light-guiding member that illuminates an illuminationtarget from an elongated light emitting face extending along alongitudinal direction of the light-guiding member by guiding light fromthe light source portion, and a holding member that holds thelight-guiding member.

Specifically, an illuminating device has been disclosed which includes alight-emitting body formed by arranging a plurality of light-emittingelements in a line, which reflects light from the light-emitting elementwith a reflecting member, and emits the reflected light toward thereading range of the document via the light-guiding member held by theholding member (for example, see FIGS. 7 to 10 and FIG. 13 of PatentDocument 1 cited below).

PRIOR ART DOCUMENT Patent Document

Patent Document 1: JP2008-172562A

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

However, image reading apparatuses as disclosed in Patent Document 1have the following problems.

That is, since the light-guiding member is fixed to the holding member,it is difficult to replace the light-guiding member when thelight-guiding member needs to be replaced due to scratches, cracking orthe like.

Furthermore, while the reflecting member is configured to guide lightfrom the light-emitting element to the light-guiding member, noconsideration is given to light from the light emitting face of thelight-guiding member to the illumination target, and thus lightirradiated onto the illumination target from the light emitting face ofthe light-guiding member tends to be scattered, thereby inviting loss ofirradiation light from the light emitting face to the illuminationtarget. Particularly, the amount of light produced by light sourcesformed of light-emitting elements such as LEDs tends be smaller thanthat by bar-shaped light sources such as a halogen lamp, and thereforeit is desirable to increase the amount of light irradiated onto theillumination target described above.

In view of the above, the present invention aims at providing anilluminating device, an image reading apparatus and an image formingapparatus, in which the light-guiding member can be easily replaced withrespect to the holding member, and the amount of irradiation light fromlight emitting face of the light-guiding member onto the illuminationtarget can be increased.

Means for Solving the Problems

In order to address the above-described issues, the present inventionprovides an illuminating device including: a light source portion, atranslucent elongated light-guiding member for illuminating anillumination target from an elongated light emitting face that extendsin a longitudinal direction, by guiding light from the light sourceportion, and a holding member for holding the light-guiding member,wherein the holding member includes a holding portion for removablyholding the light-guiding member and a tilted portion that reflectslight from the light source portion that passes through thelight-guiding member and that is emitted from the light emitting face,the tilted portion extending from a front end on the light emitting faceside of the holding portion, obliquely widening with increasing distancefrom the light-guiding member.

Also, the present invention provides an image reading apparatusincluding an illuminating device of the present invention.

Also, the present invention provides an image forming apparatusincluding an image reading apparatus of the present invention.

With the present invention, the holding portion of the holding memberremovably holds the light-guiding member, and therefore when thelight-guiding member needs to be replaced, the light-guiding member canbe easily replaced with respect to the holding member. In addition, thetilted portion of the holding member extends from the front end on thelight emitting face side of the holding portion so as to obliquely widenas the distance from the light-guiding member increases. Therefore, thelight-guiding member can be smoothly attached to the holding portionalong the tilted portion. Also, the tilted portion of the holding memberreflects light emitted by the light source portion and emitted from thelight emitting face via the light-guiding member, and therefore lightfrom the light emitting face can be can be effectively condensed on theillumination target. In this manner, the amount of irradiation lightonto the illumination target from the light emitting face can beincreased. This configuration of the tilted portion is effectiveparticularly in the case where a light source portion made up of alight-emitting element such as LED is used as the light source portion.That is, by the configuration of the tilted portion, the amount ofirradiation light onto the illumination target from the light emittingface can be effectively increased with respect to light from a lightsource portion made up of a light-emitting element such as LED, whoselight amount tends to be smaller than that of a bar-shaped light sourceportion such as halogen lamp.

In the present invention, a holding face of the holding portion forholding the light-guiding member preferably serves as a reflecting facefor reflecting light inside the light-guiding member.

With this specific feature, light loss by reflection inside thelight-guiding member can be suppressed by the holding face of theholding portion serving as the reflecting face, and the amount ofirradiation light onto the illumination target from the light emittingface can be increased by that amount of suppressed light loss.

The holding portion and the tilted portion may be formed by a metalmaterial such as stainless steel (SUS), for example.

In the present invention, a reflecting member is preferably provided atthe holding face of the holding portion for holding the light-guidingmember and at an inner face of the tilted portion.

With this specific feature, light loss by reflection inside thelight-guiding member can be suppressed due to the reflecting memberprovided in the holding face of the holding portion. In addition, lightloss by reflection in light emitted from the light emitting face can besuppressed by the reflecting member provided in the inner face of thetilted portion, and the amount of irradiation light onto theillumination target from the light emitting face can be increased bythat amount of suppressed light loss. The reflecting member can beformed by a reflection film, for example.

In the present invention, the holding portion preferably holds thelight-guiding member in a state of close contact.

With this specific feature, as a result of the holding portion holdingthe light-guiding member in close contact thereto, light leak in thelight-guiding member can be suppressed. Accordingly, light loss byreflection inside the light-guiding member can be suppressed.

In another example of the present invention, the light source portion isprovided on both sides in the longitudinal direction of thelight-guiding member, and the light-guiding member irradiates theillumination target with light from the light emitting face by guidinglight from the light source portion on one side from one end face in thelongitudinal direction, and guiding light from the other light sourceportion on the other side from the other end face in the longitudinaldirection.

Specific examples of the above mode will be described below, namely,

(a) a mode in which the holding portion is formed in a quadrangularshape with one open side when viewed from the side in the longitudinaldirection, and removably holds the light-guiding member fitted to aninner face of the holding portion, a length in a width direction at theopen end of the holding portion having the quadrangular shape with oneopen side when viewed from the side in the longitudinal direction isshorter than a length in the width direction at a base end of theholding portion;(b) a mode in which the holding portion is formed in a quadrangularshape with one open side when viewed from the side in the longitudinaldirection, and removably holds the light-guiding member fitted to theinner face of the holding portion, the light-guiding member is formed ina square or a rectangular shape when viewed from the side in thelongitudinal direction, and the length in the width direction at theopen end of the holding portion having the quadrangular shape with oneopen side when viewed from the side in the longitudinal direction isshorter than a length in a width direction of the light-guiding member;and(c) a mode in which the foregoing modes (a) and (b) are combined.

With the above modes (a) to (c), it is possible to reliably hold thelight-guiding member on the open side of the quadrangular holdingportion with one open side when viewed from the side in the longitudinaldirection. Accordingly, the light-guiding member and the holding portioncan be in closer contact to each other, and the light leak in thelight-guiding member can be suppressed correspondingly. As a result,light loss inside the light-guiding member can be further suppressed.

In the present invention, the holding portion is preferably formed of ametal material having elasticity.

With this specific feature, the light-guiding member and the holdingportion can be in closer contact to each other, and in addition, theholding portion elastically deforms when holding the light-guidingmember. Therefore, even though the light-guiding member is repeatedlyreplaced, the light-guiding member can be stably held for a long periodof time.

Effects of the Invention

As described above, with an illuminating device, an image readingapparatus and an image forming apparatus of the present invention, as aresult of the holding portion of the holding member removably holdingthe light-guiding member, when the light-guiding member needs to bereplaced, the light-guiding member can be easily replaced with respectto the holding member. Furthermore, since the tilted portion of theholding member reflects light emitted by the light source portion andemitted from the light emitting face via the light-guiding member, andextends from the front end on the light emitting face side of theholding portion so as obliquely widen as the distance from thelight-guiding member increases, the light-guiding member can be smoothlyattached to the holding portion along the tilted portion. In addition,light from the emitting face can be effectively condensed on theillumination target, thereby increasing the amount of irradiation lightonto the illumination target from the light emitting face.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view schematically illustrating an image formingapparatus provided with an image reading apparatus to which anilluminating device according to an embodiment of the present inventionis applied.

FIG. 2 is a schematic cross-sectional view of the image readingapparatus shown in FIG. 1.

FIG. 3 is a schematic perspective view of the image reading apparatusshown in FIG. 1.

FIG. 4 is a schematic perspective view showing a general configurationof a light source unit according to the embodiment.

FIG. 5 is a schematic perspective view illustrating a light sourcelight-guiding member unit of the light source unit.

FIGS. 6(a) and 6(b) are schematic views of a light source substrate ofthe light source unit, where FIG. 6(a) is a front view of the lightsource substrate and FIG. 6(b) is a side view of the light sourcesubstrate.

FIGS. 7(a) and 7(b) are schematic side views of a main part of the lightsource unit as viewed from both sides in a longitudinal directionthereof. FIG. 7(a) is a diagram from one side, and FIG. 7(b) is adiagram from the other side.

FIGS. 8(a) and 8(b) are schematic cross-sectional views illustratinglight reflection states with first and second light-guiding members.FIG. 8(a) shows a reflection state of light that is irradiated on adocument from the light emitting face by guiding light from two firstlight source portions whose emission faces oppose each other from bothend faces in the longitudinal direction. FIG. 8(b) shows a reflectionstate of light that is irradiated on a document from the light emittingface by guiding light from two second light source portions whoseemission faces oppose each other from both end faces in the longitudinaldirection.

FIG. 9 is a schematic cross-sectional view showing an example of thereflection state of light that is irradiated on a document from theinside of the first and second light-guiding members held by the firstand second holding members of a base via the light emitting face, asviewed from one side in the longitudinal direction.

FIGS. 10(a), 10(b) and 10(c) are diagrams illustrating the configurationof the first and second light-guiding members held by the first andsecond holding members of the base. FIG. 10(a) is a schematiccross-sectional view of the first and second holding members and thefirst and second light-guiding members from one side in the longitudinaldirection, FIG. 10(b) is a schematic side view of the first and secondlight-guiding members as viewed in the longitudinal direction, and FIG.10(c) is a schematic side view of the first and second holding membersas viewed in the longitudinal direction.

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described below withreference to the drawings. Note that the following embodiment is anexample of embodying the invention, and does not limit the technicalscope of the invention.

FIG. 1 is a side view schematically showing an image forming apparatus Dprovided with an image reading apparatus 100 to which an illuminatingdevice according to an embodiment of the present embodiment is applied.

The image forming apparatus D shown in FIG. 1 is provided with the imagereading apparatus 100 that reads an image of a document G (see FIG. 2 tobe described later) as an illumination target and an apparatus main bodyD1 that records and forms the image on the document G read by the imagereading apparatus 100 or images received from an outside source in coloror in monochrome on a recording sheet such as plain paper.

Overall Configuration of Image Forming Apparatus

The apparatus main body D1 of the image forming apparatus D includes anexposure device 1, developing devices 2 (2 a, 2 b, 2 c and 2 d),photosensitive drums 3 (3 a, 3 b, 3 c and 3 d) that function as imagecarriers, charging devices 5 (5 a, 5 b, 5 c and 5 d), cleaning devices 4(4 a, 4 b, 4 c and 4 d), an intermediate transfer belt device 8 thatincludes intermediate transfer rollers 6 (6 a, 6 b, 6 c and 6 d) thatfunctions as transfer portion, a fixing device 12, a sheet transportdevice 50, a paper feed tray 10 that functions as a paper feed portion,and a paper discharge tray 15 that functions as a paper dischargeportion.

Image data handled in the apparatus main body D1 of the image formingapparatus D corresponds to a color image using the colors black (K),cyan (C), magenta (M), and yellow (Y), or corresponds to a monochromeimage using a single color (e.g., black). Accordingly, four each of thedevelopment apparatuses 2 (2 a, 2 b, 2 c and 2 d), the photosensitivedrums 3 (3 a, 3 b, 3 c and 3 d), the charging devices 5 (5 a, 5 b, 5 cand 5 d), the cleaner apparatuses 4 (4 a, 4 b, 4 c and 4 d), and theintermediate transfer rollers 6 (6 a, 6 b, 6 c and 6 d) are provided soas to form four images corresponding to the respective colors, thusforming four image stations. The suffix letters a to d respectivelycorrespond to black, cyan, magenta, and yellow. In the descriptionbelow, the suffix letters a to d are omitted.

The photosensitive drums 3 are arranged substantially in the center ofthe apparatus main body D1 with respect to the vertical direction.

The charging devices 5 are charging means for evenly charging thesurface of the photosensitive drums 3 to a predetermined potential, andmay be of the roller type or of the brush type, which are contact types,but may also be of the charger type.

The exposure device 1 is a laser scanning unit (LSU) including a laserdiode and a reflecting mirror, and exposes the surface of the chargedphotosensitive drums 3 to light according to image data, thereby formingon the surface an electrostatic latent image according to the imagedata.

The developing devices 2 develop an electrostatic latent image formed onthe photosensitive drums 3 with four colors (K, C, M and Y) of toners.The cleaning devices 4 remove and collect toner remaining on the surfaceof the photosensitive drums 3 after developing and transferring animage.

The intermediate transfer belt device 8 arranged above thephotosensitive drums 3 includes, other than the intermediate transferrollers 6, an intermediate transfer belt 7, an intermediate transferbelt drive roller 21, an idler roller 22, a tension roller 23 and anintermediate transfer belt cleaning device 9.

Roller members such as the intermediate transfer belt drive roller 21,the intermediate transfer rollers 6, the idler roller 22, the tensionroller 23 or the like support the intermediate transfer belt 7 in astretched and tensioned manner, and rotate the intermediate transferbelt 7 around in a prescribed sheet transport direction (direction ofthe arrow in the drawing).

The intermediate transfer rollers 6 are rotatably supported inside theintermediate transfer belt 7, and pressed against the photosensitivedrums 3 via the intermediate transfer belt 7.

The intermediate transfer belt 7 is provided contacting the respectivephotosensitive drums 3, and the toner images on the surfaces of therespective photosensitive drums 3 are sequentially transferred andsuperposed on the intermediate transfer belt 7, forming a color tonerimage (a toner image containing the respective colors). Here, thetransfer belt 7 is formed as an endless belt using a film having athickness of 100 μm to 150 μm, approximately.

The toner images are transferred from the photosensitive drums 3 to theintermediate transfer belt 7 using the intermediate transfer rollers 6pressed against the inner side (back face) of the intermediate transferbelt 7. A high-voltage transfer bias (for example, a high voltage of theopposite polarity (+) to the charge polarity (−) of the toner) isapplied to the intermediate transfer rollers 6 for transferring thetoner images. The intermediate transfer rollers 6 are rollers includinga base that is made of a metal (e.g., stainless steel) shaft having adiameter of 8 to 10 mm, the surface of the shaft being covered by anelectrically conductive elastic material (e.g., EPDM, urethane foam,etc.). The electrically conductive elastic material enables a highvoltage to be evenly applied to a recording sheet.

The apparatus main body D1 of the image forming apparatus D furtherincludes a secondary transfer device 11 that includes a transfer roller11 a functioning as a transfer portion. The transfer roller 11 acontacts the outer side of the intermediate transfer belt 7.

As described above, toner images on the surfaces of the respectivephotosensitive drums 3 are superposed on the intermediate transfer belt7, forming a toner image of colors represented by the image data. Thetoner images of the respective colors superposed in this manner aretransported with the intermediate transfer belt 7, and are transferredon a recording sheet by the secondary transfer device 11.

The intermediate transfer belt 7 and the transfer roller 11 a of thesecondary transfer device 11 are pressed to each other to form a nipregion. A voltage is applied to the transfer roller 11 a of thesecondary transfer device 11 (for example, a high voltage of theopposite polarity (+) to the charge polarity (−) of the toner) in orderto transfer the toner images of the respective colors on theintermediate transfer belt 7 to the recording sheet. Furthermore, inorder to constantly maintain the nip region, one of the transfer rollers11 a of the secondary transfer apparatus 11 and the intermediatetransfer belt-driving roller 21 is made of a hard material (metal,etc.), and the other is made of a soft material such as an elasticroller (elastic rubber roller, foamable resin roller, etc.).

The toner image on the intermediate transfer belt 7 may not becompletely transferred by the secondary transfer apparatus 11 to therecording sheet, and toner may remain on the intermediate transfer belt7.

This residual toner causes toner color mixing in the following step.Accordingly, residual toner is removed and collected by the intermediatetransfer belt cleaning device 9. The intermediate transfer belt cleaningdevice 9 includes, for example, a cleaning blade that is in contact withthe intermediate transfer belt 7 as a cleaning member, and residualtoner can be removed and collected by the cleaning blade. The idlerroller 22 supports the intermediate transfer belt 7 from the inner side(back face), and the cleaning blade is in contact with the intermediatetransfer belt 7 to press from outside against the idler roller 22.

The paper feed tray 10 is a tray in which recording sheets are stored,and is disposed below the image forming portion of the apparatus mainbody D1. The paper discharge tray 15 disposed above the image formingportion is a tray on which printed recording sheets are placed facedown.

In addition, in the apparatus main body D1 is provided the sheettransport device 50 for feeding the recording sheet in the paper feedtray 10 to the paper discharge tray 15 via the secondary transfer device11 and the fixing device 12. The sheet transport device 50 includes anS-shaped sheet transport path S, and transport members such as a pickuproller 16, an isolating roller 14 a, a separation roller 14 b, transportrollers 13, a pre-registration roller pair 19, a registration rollerpair 106, the fixing device 12 and discharge rollers 17 are arrangedalong the sheet transport path S.

The pickup roller 16 is a draw-in roller that is disposed in adownstream side end portion in the sheet transport direction of thepaper feed tray 10 and that feeds recording sheets sheet by sheet fromthe paper feed tray 10 into the paper transport path S. The isolatingroller 14 a allows recording sheets to pass between the isolating roller14 a and the separation roller 14 b to separate the sheets intoindividual sheets and transports the separated sheets to the sheettransport path S. The transport rollers 13 and the pre-registrationroller pair 19 are small rollers for facilitating and assistingtransportation of the recording sheets. The transport rollers 13 aredisposed in plural locations in the sheet transport path S. Thepre-registration roller pair 19 is disposed in a position right beforethe registration roller pair 106 on the upstream side in the sheettransport direction, and transports the recording sheet to theregistration roller pair 106.

The fixing device 12 receives a recording sheet onto which a toner imagehas been transferred, and transports the recording sheet whilesandwiching the recording sheet between a heating roller 31 and apressure roller 32.

The temperature of the heating roller 31 is controlled to a prescribedfixing temperature, and performs thermal pressing on the recording sheetwith the pressure roller 32 to melt, mix and press the toner imagestransferred on the recording sheet, thereby thermally fixing the tonerimages on the recording sheet.

After the toner images of the respective colors are fixed, the recordingsheet is discharged to the paper discharge tray 15 by the dischargerollers 17.

Note that it is possible to form a monochrome image by using only one ofthe four image forming stations, and transfer the monochrome image tothe intermediate transfer belt 7 of the intermediate transfer beltdevice 8. The monochrome image is also transferred to the recordingsheet from the intermediate transfer belt 7, similarly to the colorimage, and fixed on the recording sheet.

Also, in the case where an image is formed not only on the front face ofthe recording sheet, but on both faces, after the image on the frontface of the recording sheet is fixed by the fixing device 12, thedischarge rollers 17 are stopped while the recording sheet istransported by the discharge rollers 17 in the sheet transport path S,and then discharge rollers 17 are rotated in reverse to allow therecording sheet to pass a front-back reverse route Sr. The front andback faces of the recording sheet are then inverted, and the recordingsheet is again guided to the registration roller pair 106. Then, animage is recorded and fixed on the back face of the recording sheetsimilarly to the front face of the recording sheet, and the recordingsheet is discharged to the paper discharge tray 15.

Overall Configuration of Image Reading Apparatus

FIG. 2 is a schematic cross-sectional view of the image readingapparatus 100 shown in FIG. 1. FIG. 3 is a schematic perspective view ofthe image reading apparatus 100 shown in FIG. 1.

The image reading apparatus 100 shown in FIGS. 1 to 3 is provided with aconfiguration to read a document image while keeping the document Gfixed in a stationary document reading arrangement, and a configurationto read a document image while moving the document G in a movingdocument reading arrangement.

That is, the image reading apparatus 100 has a stationary documentreading configuration in which document G placed on a platen glass 201 ais illuminated by a light source portion 211 via the platen glass 201 a,and the document image is read by scanning light reflected from thedocument G that is illuminated by the light source portion 211 in a mainscanning direction (direction of the arrow Y in the drawing) while thelight source portion 211 is moved in a sub-scanning direction (directionof the arrow X in the drawing), and a moving document readingconfiguration in which while illuminating the document G transported byan automatic document feeder 300 in the sub-scanning direction X so asto pass over a document reading glass 201 b by the light source portion211 positioned at a home position P in a document reading portion 200via the glass 201 b, reflected light from the document G illuminated bythe light source portion 211 is scanned in the main scanning directionY, thereby reading the document image. Note that FIG. 2 shows a state inwhich the light source portion 211 is in the home position P. Also, inFIG. 3, the automatic document feeder 300, a mirror unit 203 describedbelow or the like are not shown.

Specifically, the document reading portion 200 includes the platen glass201 a, a light source unit 210 including the light source portion 211(example of the illuminating device), an optical system driving portionthat moves the light source portion 211 (not shown), the mirror unit203, a condensing lens 204 and an imaging element (here, CCD) 205. Also,the light source portion 211 is disposed in the light source unit 210.These are accommodated in a metal frame (hereinafter referred to as a“frame body”) 202. Note that the light source unit 210 will be describedin detail later.

The platen glass 201 a is made of a transparent glass plate, and bothend portions thereof in the main scanning direction Y are placed on theframe body 202. Note that the automatic document feeder 300 is capableof opening and closing with respect to the document reading portion 200about an axis line along the sub-scanning direction X (pivotablysupported by a hinge, for example), and its bottom face also functionsas a document pressing member for pressing the document G placed on theplaten glass 201 a of the document reading portion 200 from above.

The mirror unit 203 includes a second mirror 203 a, a third mirror 203 band a supporting member (not shown). The supporting member supports thesecond mirror 203 a so as to reflect light from the first mirror 230 inthe light source unit 210 to be guided to the third mirror 203 b, andalso supports the third mirror 203 b so as to reflect light from thesecond mirror 203 a to be guided to the condensing lens 204. Thecondensing lens 204 condenses light from the third mirror 203 b to theimaging element 205. The imaging element 205 converts light from thecondensing lens 204 (document image light) to electric signals as imagedata.

In addition, the optical system driving portion is configured to movethe light source unit 210 at a constant speed in the sub-scanningdirection X, and at the same time, move the mirror unit 203 at a movingspeed that is half the moving speed of the light source unit 210 also inthe sub-scanning direction X.

Here, the document reading portion 200 supports not only the stationarydocument reading arrangement, but also the moving document readingarrangement as well, and thus includes the document reading glass 201 b.Accordingly, the optical system driving portion is further configured toposition the light source unit 210 in a prescribed home position P belowthe document reading glass 201 b. Note that although the platen glass201 a and the document reading glass 201 b are independent elements inthis embodiment, they may be formed as one element.

The automatic document feeder 300 includes a document tray 301 on whichthe document G is placed for transportation, a discharge tray 302arranged below the document tray 301, a first transport path 303 thatconnects the document tray 301 and the discharge tray 302, and twotransport roller pairs including an upstream side transport roller pair304 and a downstream side transport roller pair 305 that transport thedocument G on the upstream side and downstream side, respectively, in atransport direction X1 of the document G, with respect to the documentreading glass 201 b. Specifically, the upstream side transport rollerpair 304, the document reading glass 201 b and the downstream sidetransport roller pair 305 are arranged in this order in the transportdirection X1. Also, the document reading glass 201 b is disposedsubstantially horizontally so as to form the transport wall of the firsttransport path 303.

The automatic document feeder 300 further includes a pickup roller 306,an isolating roller 307 and a separation member 308 such as a separationpad.

The pickup roller 306 feeds forward the document G placed on thedocument tray 301 from the document tray 301 to the first transport path303 in the transport direction X1. The isolating roller 307 is arrangedon the downstream side in the transport direction X1 relative to thepickup roller 306, and sandwiches the document G sent by the pickuproller 306 with the separation member 308, and further transports thedocument G to the downstream side in the transport direction X1. Theseparation member 308 is opposed to the isolating roller 307 andsingularizes (separates) the documents G transported therebetween intoindividual sheets.

The automatic document feeder 300 configured as described abovetransports the documents G up to between the isolating roller 307 andthe separation member 308 by the pickup roller 306, where the documentsG are singularized and separated and are at the same time transportedsheet by sheet as a result of the isolating roller 307 being driven torotate. Then, the document G transported by the isolating roller 307 isguided by the first transport path 303, thereby making it possible tofeed the document G sheet by sheet toward the upstream side transportroller pair 304.

Specifically, the pickup roller 306 can contact and be separated fromthe document G placed on the document tray 301 with the use of a pickuproller drive portion not shown in the drawings. In addition, the pickuproller 306 is connected to the isolating roller 307 via a drivetransmission means 309 including an endless belt or the like so as torotate in the same direction as the isolating roller 307. When there isa request to read the document G, the pickup roller 306 and theisolating roller 307 are driven by a document feed drive portion notshown in the drawings to rotate in a direction with which the document Gis transported in the transport direction X1 (the arrow H in FIG. 2).

In the present embodiment, the automatic document feeder 300 is alsoconfigured such that, after transporting the document G so as to enablereading one face thereof, the document G can be inverted so as toreverse the front and back faces thereof, thereby transporting thedocument G so as to enable reading the other face thereof.

Specifically, in addition to the above-described configuration, theautomatic document feeder 300 further includes a reverse roller pair310, a second transport path 311 and a switching claw 312.

The first transport path 303 is formed as a loop to transport thedocument G from the isolating roller 307 to the discharge tray 302, viathe upstream side transport roller pair 304, document reading glass 201b, downstream side transport roller pair 305 and reverse roller pair310. The reverse roller pair 310 is disposed on the downstream side inthe transport direction X1 relative to the downstream side transportroller pair 305, and transports the document G transported from thedownstream side transport roller pair 305 such that the trailing end ofthe document G (the upstream side end in the transport direction X1) isin the front. The second transport path 311 is branched at a branchportion S1 between the reverse roller pair 310 and the downstream sidetransport roller pair 305, and guides the document G transported suchthat the trailing end thereof is in the front to the further upstreamside in the transport direction X1 than the upstream side transportroller pair 304 of the first transport path 303, in order to invert thefront and back faces of the document G. A switchback transport path 313is formed between the reverse roller pair 310 and the branch portion S1of the first transport path 303. The switchback transport path 313 iscapable of transportation of the document G by forward rotation of thereverse roller pair 310 (the transport direction X1 of the document G)and reverse transportation of the document G by reverse rotation of thereverse roller pair 310.

The switching claw 312 is arranged in the branch portion S1, and isconfigured to be capable of taking a first switching posture in whichthe document G is guided to the upstream side transport roller pair 304from the reverse roller pair 310 via the second transport path 311, anda second switching posture in which the document G is guided to thereverse roller pair 310 from the downstream side transport roller pair305 via the switchback transport path 313.

Here, in a normal state, the switching claw 312 is arranged directlyconnecting the switchback transport path 313 and the second transportpath 311 (first switching posture, see the solid line in FIG. 2). Whenthe document G whose document image has been read by the documentreading portion 200 is transported in the transport direction X1, theleading end of the document G (the downstream side end in the transportdirection X1) pushes up the switching claw 312 to guide the document Gto the switchback transport path 313 (second switching posture, see thedashed line in FIG. 2). The branching claw 312 is capable of freelyswaying about a swaying axis Q along the axis line direction of thereverse roller pair 311 such that a claw portion 312 a drops due to itsown weight, thereby blocking the first transport path 303 between thedownstream side transport roller pair 305 and the reverse roller pair310 to take the first switching posture. When the trailing end of thedocument G is positioned in the switchback transport path 313, and thedocument G is transported in reverse in a reverse-transport direction(direction of the arrow X2 in FIG. 2) that is the opposite direction tothe transport direction X1 of the document G by the reverse roller pair310 rotating in the reverse direction, the switching claw 312 guides thedocument G to the second transport path 311.

Note that the size of the document G placed on the document tray 301 isdetected by a document size sensor 314 disposed in a document placementportion of the document tray 301. Whether a document G is placed on thedocument tray 301 or not is detected by a document detecting sensor 315disposed near the pickup roller 306 of the document placement portion ofthe document tray 301. Also, in a stopped state, the upstream sidetransport roller pair 304 causes the leading end of the document Gtransported by the isolating roller 307 to abut against the same foralignment, and is driven to rotate in accordance with the timing forreading. The document G thus transported is detected by a transportsensor 316 that is disposed on the further downstream side than thesecond transport path 311 and also on the further downstream side thanthe upstream side transport roller pair 304, in the transport directionX1 of the first transport path 303. The document G discharged by thereverse roller pair 310 is detected by a discharge sensor 317 disposednear the reverse roller pair 310 on the discharge side relative to thereverse roller pair 310. Note that the transport roller pairs 304 and305, reverse roller pair 310 or the like are driven by a transportsystem drive portion, which is not shown.

Also, in the present embodiment, the automatic document feeder 300further includes a reading guide 318 that faces the document readingglass 201 b with the document G interposed therebetween.

In the image reading apparatus 100 described above, when an instructionto read the document image of the document G by the stationary documentreading arrangement is made, the light source unit 210 moves to one sidein the sub-scanning direction X at a constant speed while irradiatingthe document G placed on the platen glass 201 a with light via theplaten glass 201 a, thereby scanning the image of the document G. At thesame time, the mirror unit 203 also moves to the one side in thesub-scanning direction X at a moving speed that is half the moving speedof the light source unit 210.

Reflected light from the document G illuminated by the light source unit210 is reflected by the first mirror 230 provided in the light sourceunit 210 and then the optical path of which is converted by 180° by thesecond and third mirrors 203 a and 203 b of the mirror unit 203. Lightreflected by the third mirror 203 b forms an image on the imagingelement 205 via the condensing lens 204, and here the document imagelight is read to be converted to electric image data.

When an instruction to read the document image on the document G by themoving document reading system is made, automatic document feeder 300transports the document G to one side in the sub-scanning direction X soas to pass a portion above the position indicated in FIG. 2, while thelight source unit 210 and the mirror unit 203 staying in the positionindicated in FIG. 2. That is, the documents G placed on the documenttray 301 are taken out by the pickup roller 306, separated by theisolating roller 307 and the separation member 308 into individualsheets, and transported to the first transport path 303. Aftertransportation of the document G is confirmed by the transport sensor316, the leading end of the document G transported to the firsttransport path 303 is aligned to prevent slanted transportation of thedocument G and sent out at a prescribed timing for reading by theupstream side transport roller pair 304, then the front and back facesare inverted and transported to the document reading glass 201 b.

Onto one face of the document G that passes above the document readingglass 201 b, light from the light source unit 210 is irradiated via thedocument reading glass 201 b and reflected by the one face. The lightreflected by the one face of the document G is reflected by the firstmirror 230 similarly to the above-described stationary document readingarrangement, and thereafter the optical path of which is converted by180° by the second and third mirrors 203 a and 203 b of the mirror unit203. Light reflected from the third mirror 203 b forms an image on theimaging element 205 via the condensing lens 204, and here the documentimage is read and converted to electric image data. Note that thisreading operation by the imaging element 205 is the same in the case ofduplex reading to be described later, and the operation will not bedescribed below.

The document G that has been read is drawn off the reading glass 201 bythe downstream side transport roller pair 305, and discharged onto thedischarge tray 302 by the reverse roller pair 310, which is capable offorward and reverse rotation via the switchback transport path 313 ofthe first transport path 303.

Also, in the case where both of one face and the other face of thedocument G are read, the document G one face of which has been read isnot discharged to the discharge tray 302, but transported such that thetrailing end thereof is positioned in the switchback transport path 313.The document G is then transported in reverse in the reverse-transportdirection X2 by the reverse roller pair 310 rotating in reverse, andguided to the second transport path 311 by the switching claw 312 in thefirst switching posture. The document G guided to the second transportpath 311 is again returned to the first transport path 303 via thesecond transport path 311 and as a result, the document G is transportedby the upstream side transport roller pair 304 with the front and backfaces thereof inverted, passes above the document reading glass 201 b,and thus the other face of which is read. The document G both faces ofwhich have been read again returns to the first transport path 303 andis transported by the transport roller pairs 304 and 305 with the frontand back faces thereof inverted. Thereafter, the document G passes theswitchback transport path 313 of the first transport path 303, and isdischarged to the discharge tray 302 via the reverse roller pair 310rotating in the forward direction.

Description of Characteristic Portions of the Invention

A light source unit according to an embodiment of the invention may beconfigured to include one or two or more light-guiding members. Here, alight source unit 210 including two light-guiding members, namely firstand second light-guiding members 213 a and 213 b, will be describedbelow as an example.

FIG. 4 is a schematic perspective view showing a schematic configurationof the light source unit 210 according to the present embodiment. FIG. 5is a schematic perspective view illustrating a light sourcelight-guiding member unit 220 of the light source unit 210.

Also, FIG. 6 is a schematic view showing two light source substrates2121 and 2122 of the light source unit 210. FIG. 6(a) shows a front viewof the light source substrates 2121 and 2122, and FIG. 6(b) shows a sideview of the light source substrates 2121 and 2122. Note that the twolight source substrates 2121 and 2122 are members having the sameconfiguration, which are shown by a single diagram in FIG. 6. Also, inFIG. 6, reference numeral C1 indicates the seatings of light sourceportions 211 a 1, 211 b 1, 211 a 2 and 211 b 2, reference numeral C2indicates a connecter terminal, and reference numeral C3 indicatesattachment screw holes of the light source substrates 2121 and 2122.

Also, FIG. 7 is a schematic side view of a main part of the light sourceunit 210 as viewed from both sides in the longitudinal direction. FIG.7(a) is a diagram as viewed from one side, and FIG. 7(b) is a diagram asviewed from the other side. Note that in FIG. 7, the seating C1, theconnector terminal C2 and the attachment screw hole C3 are not shown.

FIG. 8 is a schematic cross-sectional view illustrating light reflectionstates in the first and second light-guiding members 213 a and 213 b.FIG. 8(a) shows a reflection state of light that is irradiated on thedocument G from a light emitting face M by guiding light from the twofirst light source portions 211 a 1 and 211 a 2 whose emission facesoppose each other from both end faces 213 a 1 and 213 a 2 in thelongitudinal direction Y. FIG. 8(b) shows a reflection state of lightthat is irradiated on the document G from the light emitting face M byguiding light from the two second light source portions 211 b 1 and 211b 2 whose emission faces oppose each other from both end faces 213 b 1and 213 b 2 in the longitudinal direction Y. Note that in FIG. 8, theglass provided between the document and the light source portion is notshown.

The light source unit 210 includes the two light source substrates 2121and 2122, first and second light-guiding members 213 a and 213 b, a basebody 214, and first and second reflecting members (here, reflectionfilm) 215 a and 215 b.

In the present embodiment, one of the two light source substrates 2121and 2122, the light source substrate 2121, is formed by forming a firstlight source substrate 212 a 1 on one side, and a second light sourcesubstrate 212 b 1 on one side in one piece (see FIG. 6). The first lightsource portion 211 a 1 on the one side, which emits light to the firstlight-guiding member 213 a, is mounted to the first light sourcesubstrate 212 a 1 on the one side. The second light source portion 211 b1 on the one side, which emits light to the second light-guiding member213 b is mounted to the second light source substrate 212 b 1 on the oneside. Out of the two light source substrates 2121 and 2122, the lightsource substrate 2122 on the other side is formed by forming a firstlight source substrate 212 a 2 on the other side and a second lightsource substrate 212 b 2 on the other side in one piece (see FIG. 6). Afirst light source portion 211 a 2 on the other side, which emits lightto the first light-guiding member 213 a is mounted to the first lightsource substrate 212 a 2 on the other side. A second light sourceportion 211 b 2 on the other side, which emits light to the secondlight-guiding member 213 b is mounted to the second light sourcesubstrate 212 b 2 on the other side. Note that the light source portionscorrespond to the element denoted by the reference numeral 211 in FIG.2.

Specifically, the first and second light source portions 211 a 1 and 211b 1 on the one side, and the first and second light source portions 211a 2 and 211 b 2 on the other side are all LED light source portions madeup of an LED light-emitting element.

The first and second light-guiding members 213 a and 213 b are each madeof a translucent material, and have an elongated shape extending in themain scanning direction Y. The first and second light-guiding members213 a and 213 b are disposed side by side in the sub-scanning directionX that extends along the light irradiation face of the document G at aprescribed interval such that their longitudinal directions Y match eachother.

The first light-guiding member 213 a guides light from the first lightsource portion 211 a 1 on the one side from one end face 213 a 1 in thelongitudinal direction Y, and at the same time guides light from thefirst light source portion 211 a 2 on the other side from the other endface 213 a 2 in the longitudinal direction Y, thereby irradiating lighton the document G from the light emitting face (top face) M extending inthe longitudinal direction Y (see FIG. 8(a)). The second light-guidingmember 213 b guides light from the second light source portion 211 b 1on the one side from the end face 213 b 1 on the one side in thelongitudinal direction Y, and guides light from the second light sourceportion 211 b 2 on the other side from the end face 213 b 2 on the otherside in the longitudinal direction Y, thereby irradiating light on thedocument G from the light emitting face (top face) M extending in thelongitudinal direction Y (see FIG. 8(b)).

Specifically, the first and second light-guiding members 213 a and 213 beach have a rectangular parallelepiped shape. Here, the first and secondlight-guiding members 213 a and 213 b are each formed by acrylic resin.Also, faces of the first and second light-guiding members 213 a and 213b positioned on the opposite side to the light emitting face M (i.e.bottom faces) are each indicated as a reflecting face N1. Thisreflecting face N1 is formed in a shape of minute triangles (e.g., a sawshape) when viewed from width directions Xa and Xb along the lightemitting face M, which are perpendicular to the longitudinal directionY. In addition, from the viewpoint of increasing the light amount towardthe center in the longitudinal direction Y, the gap between the peaks inthe reflecting face N1 provided with triangle shapes decreases towardthe center in the longitudinal direction Y.

As shown in FIGS. 4, 5 and 7, the base body 214 includes one fixingportion 2141 (in this case, a screw hole for fixing with a screw SC)where the one light source substrate 2121 is fixed on the side of theend faces 213 a 1 and 213 b 1 on the one side in the longitudinaldirection of the first and second light-guiding members 213 a and 213 b,and another fixing portion 2142 (in this case, a screw hole for fixingwith a screw SC) where the other light source substrate 2122 is fixed onthe side of the end faces 212 a 2 and 213 b 2 on the other side in thelongitudinal direction of the first and second light-guiding members 213a and 213 b. Thus, the first and second light source portions 211 a 1and 211 b 1 on the one side and the first and second light sourceportions 211 a 2 and 211 b 2 on the other side are arranged in the endfaces 213 a 1 and 213 b 1 on the one side in the longitudinal directionand the end faces 213 a 2 and 213 b 2 on the other side in thelongitudinal direction, respectively, of the first and secondlight-guiding members 213 a and 213 b.

The base body 214 further includes a first support portion 214 a forsupporting the first light-guiding member 213 a, a second supportportion 214 b for supporting the second light-guiding member 213 b, anda joining portion 214 c for connecting the first support portion 214 aand the second support portion 214 b. In the joining portion 214 cprovided between the first support portion 214 a and the second supportportion 214 b is formed a slit R for allowing reflected light from thedocument G to pass, the slit R extending in the longitudinal directionY. Note that here, the first support portion 214 a, the second supportportion 214 b and the joining portion 214 c are configured as asupporting plate 214 d that is formed in one piece.

Specifically, the first and second support portions 214 a and 214 b areeach formed to have a quadrangular shape, with one open side when viewedfrom the side in the longitudinal direction Y. That is, the first andsecond support portions 214 a and 214 b are each formed by a bottomplate extending in the longitudinal direction Y, and two side plateseach extending perpendicularly or substantially perpendicularly towardthe document G from both end portions of the bottom plate in the widthdirections Xa and Xb along the light emitting faces M that areperpendicular to the longitudinal direction Y. The first and secondsupport portions 214 a and 214 b are disposed side by side in adirection X along the light irradiation face of the document G, thedirection X being perpendicular to the longitudinal direction Y, at aprescribed interval such that the longitudinal directions Y of the firstand second support portions 214 a and 214 b match each other. Inaddition, the second support portion 214 b side of the open end of thequadrangular first support portion 214 a with one open side when viewedfrom the side is connected to the first support portion 214 a side ofthe open end of the quadrangular second support portion 214 b with oneopen side when viewed from the side by the joining portion 214 c. Theone fixing portion 2141 is provided at one of the both end portions inthe longitudinal direction Y of the joining portion 214 c, and the otherfixing portion 2142 is provided at the other end portion in thelongitudinal direction Y. Note that the first and second light-guidingmembers 213 a and 213 b are arranged so as to cause light emitted fromthe light emitting faces M thereof to mutually intersect on the lightirradiation face of the document G (in this case, so as to let theincident angles of the incident light beams entering the document Gmatch each other, when viewed from the side in the longitudinaldirection Y). Therefore, here, the first and second support portions 214a and 214 b are arranged such that the distance therebetween increasesfrom the open ends thereof toward the base ends opposite thereto whenviewed from the side in the longitudinal direction Y.

The first reflecting member 215 a mainly reflects light that passesthrough the first light-guiding member 213 a with side faces N2 on bothsides in the width direction Xa along the light emitting face M, whichis perpendicular to the longitudinal direction Y of the light-guidingmember 213 a. In contrast, the second reflecting member 215 b mainlyreflects light that passes through the second light-guiding member 213 bwith side faces N2 on both sides in the width direction Xb of thelight-guiding member 213 b (see FIG. 7).

Specifically, the first reflecting member 215 a is arranged on the facesother than the two end faces 213 a 1 and 213 a 2 of the firstlight-guiding member 213 a and the light emitting face M. The secondreflecting member 215 b is arranged on the faces other than the two endfaces 213 b 1 and 213 b 2 of the second light-guiding member 213 b andthe light emitting face M. The first and second reflecting members 215 aand 215 b are each formed by a reflection film having a high reflectance(for example, Vikuiti (registered trademark) DESR-M series (manufacturedby 3M) having a high reflectance of 98% or more), and arranged at least,out of the reflecting face N1 and the two side faces N2 of the first andsecond light-guiding members 213 a and 213 b, on the two side faces N2.

In the present embodiment, the base body 214 further includes first andsecond holding members 216 a and 216 b for holding the first and secondlight-guiding members 213 a and 213 b, respectively.

FIG. 9 is a schematic cross-sectional view as viewed from one side inthe longitudinal direction Y, showing an example of a reflection stateof light that irradiates the document G from the inside of the first andsecond light-guiding members 213 a and 213 b held by the first andsecond holding members 216 a and 216 b of the base body 214 via thelight emitting face M.

As shown in FIG. 9, the first holding member 216 a includes a firstholding portion 2161 a and a first tilted portion 2162 a. The firstholding portion 2161 a removably holds the first light-guiding member213 a. The first tilted portion 2162 a extends from the front end on thelight emitting face M side of the first holding portion 2161 a so as toreflect light emitted from the light emitting face M of the firstlight-guiding member 213 a and to obliquely widen as the distance fromthe first light-guiding member 213 a increases. Also, the second holdingmember 216 b includes a second holding portion 2161 b and a secondtilted portion 2162 b. The second holding portion 2161 b removably holdsthe second light-guiding member 213 b. The second tilted portion 2162 bextends from the front end on the light emitting face M side of thesecond holding portion 2161 b so as to reflect light emitted from thelight emitting face M of the second light-guiding member 213 b and toobliquely widen as the distance from the second light-guiding member 213b increases.

In the present embodiment, the first and second holding portions 2161 aand 2161 b are each formed to have a quadrangular shape with one openside when viewed from the side in the longitudinal direction Y. That is,the first and second holding portions 2161 a and 2161 b are each formedby a bottom plate extending in the longitudinal direction Y and two sideplates that extend perpendicularly or substantially perpendicularlytoward the document G from the two end portions of the bottom plate inthe width directions Xa and Xb along light emitting face M that areperpendicular to the longitudinal direction Y. The first and secondtilted portions 2162 a and 2162 b are each formed to obliquely widen asthe distance from the first and second light-guiding members 213 a and213 b, respectively, increases, when viewed from the side in thelongitudinal direction Y.

The quadrangular first and second holding portions 2161 a and 2161 bwith one open side when viewed from the side can have the first andsecond light-guiding members 213 a and 213 b, respectively, removablyfitted to their inner face. Thus, the first and second holding portions2161 a and 2161 b can respectively hold the first and secondlight-guiding members 213 a and 213 b reliably while they are in closecontact to the inner face of the first and second holding portions 2161a and 2161 b. In addition, the first and second holding members 216 aand 216 b are removably fitted into the first and second supportportions 214 a and 214 b, respectively. Thus, the first and secondlight-guiding members 213 a and 213 b can be respectively detached fromthe first and second holding portions 2161 a and 2161 b, with the firstand second holding members 216 a and 216 b being respectively detachedfrom the first and second support portions 214 a and 214 b, andtherefore exchangeability of the first and second light-guiding members213 a and 213 b can be improved. Also, the first and second reflectingmembers 215 a and 215 b are respectively supported by the first andsecond holding portions 2161 a and 2161 b. Note that the first andsecond holding portions 2161 a and 2161 b themselves may be formed asthe first and second reflecting members 215 a and 215 b, respectively.

For example, the first and second holding portions 2161 a and 2161 b andthe first and second tilted portions 2162 a and 2162 b may be formed ofa metal material such as stainless steel (SUS) or the like. In such acase, the first and second holding portions 2161 a and 2161 b can alsoserve as the first and second reflecting members 215 a and 215 b,respectively. As a result, the inner faces of the first and secondholding portions 2161 a and 2161 b can function as the reflecting facefor reflecting light inside the first and second light-guiding members213 a and 213 b, respectively. Note that the light source light-guidingmember unit 220 is configured by the first and second light-guidingmembers 213 a and 213 b, the first and second holding members 216 a and216 b and the supporting plate 214 d. The supporting plate 214 d and thefirst and second holding members 216 a and 216 b may be formed in onepiece.

Here, a reflection film is attached to the inner faces of the firstholding portion 2161 a and the first tilted portion 2162 a constitutingthe first holding member 216 a, as the first reflecting member 215 a.Also, a reflection film is attached to the inner faces of the secondholding portion 2161 b and the second tilted portion 2162 b constitutingthe second holding member 216 b, as the second reflecting member 215 b.

FIG. 10 is a diagram illustrating a configuration of the first andsecond light-guiding members 213 a and 213 b held by the first andsecond holding members 216 a and 216 b of the base body 214. FIG. 10(a)is a schematic cross-sectional view of the first and second holdingmembers 216 a and 216 b and the first and second light-guiding members213 a and 213 b as viewed from one side in the longitudinal direction Y.FIG. 10(b) is a schematic side view of the first and secondlight-guiding members 213 a and 213 b as viewed in the longitudinaldirection Y. FIG. 10(c) is a schematic side view of the first and secondholding members 216 a and 216 b as viewed in the longitudinal directionY. Note that in FIG. 10(b), the first and second light-guiding members213 a and 213 b have the same configuration, and therefore they areshown with a single diagram. Also, in FIG. 10(c), the first and secondholding members 216 a and 216 b have the same configuration, andtherefore they are shown with a single diagram.

Here, the quadrangular first and second holding portions 2161 a and 2161b with one open side when viewed from the side, as shown in FIG. 10(c),each have a length α (specifically, approximately 4.8 mm) in the widthdirections Xa and Xb at the open end that is shorter than their length β(specifically, approximately 5.0 mm) in the width directions Xa and Xbat the base end.

Note that the ratio (α/β) of the length α in the width directions Xa andXb at the open end to the length β in the width directions Xa and Xb atthe base end in the first and second holding portions 2161 a and 2161 bmay be approximately 0.96, for example. When this ratio (α/β) is toosmall, attaching and detaching the first and second light-guidingmembers 213 a and 213 b to and from the first and second holdingportions 2161 a and 2161 b, respectively, is difficult. On the otherhand, as the ratio approaches to 1, the first and second holdingportions 2161 a and 2161 b tend to be in looser contact to the first andsecond light-guiding members 213 a and 213 b.

Here, as shown in FIG. 10(b), the first and second light-guiding members213 a and 213 b are each formed in a square shape or rectangular shapewhen viewed from the side in the longitudinal direction Y.

In addition, here, as shown in FIGS. 10(b) and 10(c), in each of thefirst and second holding portions 2161 a and 2161 b, the length α in thewidth directions Xa and Xb at the open end is shorter than a length γ(specifically, approximately 5.0 mm) in the width directions Xa and Xbof the first and second light-guiding members 213 a and 213 b.

Note that the ratio (α/γ) of the length α in the width directions Xa andXb at the open end of the first and second holding portions 2161 a and2161 b to the length γ in the width directions Xa and Xb in the firstand second light-guiding members 213 a and 213 b may be approximately0.96, for example. When this ratio (α/γ) is too small, attaching anddetaching the first and second light-guiding members 213 a and 213 b toand from the first and second holding portions 2161 a and 2161 b,respectively, is difficult. On the other hand, as the ratio approaches1, the first and second holding portions 2161 a and 2161 b tend to be inlooser contact to the first and second light-guiding members 213 a and213 b.

In the present embodiment, the first and second holding portions 2161 aand 2161 b are each formed by a metal material having elasticity.

The light source unit 210 further includes the first mirror 230 (seeFIG. 2). The first mirror 230 is supported by a supporting member notshown in the drawings so as to guide light reflected by the lightirradiation face of the document G to the second mirror 203 a of themirror unit 203 via the slit R provided in the joining portion 214 c ofthe base body 214.

With the light source unit 210 described above, the first and secondholding portions 2161 a and 2161 b of the first and second holdingmembers 216 a and 216 b removably hold the first and secondlight-guiding members 213 a and 213 b (here, have the first and secondlight-guiding members 213 a and 213 b fitted thereto), respectively. Forthis reason, when the first and second light-guiding members 213 a and213 b need to be replaced, the first and second light-guiding members213 a and 213 b can be easily replaced with respect to the first andsecond holding members 216 a and 216 b, respectively. Furthermore, inthe light source unit 210, the first and second tilted portions 2162 aand 2162 b of the first and second holding members 216 a and 216 b eachextend from the front end on the light emitting face M side of the firstand second holding portions 2161 a and 2161 b so as to obliquely widenas the distance from the first and second light-guiding members 213 aand 213 b increases. Therefore, the first and second light-guidingmembers 213 a and 213 b can be smoothly fitted into the first and secondholding members 216 a and 216 b along the first and second tiltedportions 2162 a and 2162 b. In addition, in the light source unit 210,the first and second tilted portions 2162 a and 2162 b of the first andsecond holding members 216 a and 216 b respectively reflect lightemitted by the light source portions 211 a 1, 211 b 1, 211 a 2 and 211 b2 and emitted from the light emitting face M via the first and secondlight-guiding members 213 a and 213 b. As a result, light from the lightemitting face M can be effectively condensed on the light irradiationface of the document G, thereby making it possible to increase theamount of irradiation light onto the light irradiation face of thedocument G from the light emitting face M.

Furthermore, in the light source unit 210, the holding faces (the innerfaces in this case) of the first and second holding portions 2161 a and2161 b serve as the reflecting face on which the light inside the firstand second light-guiding members 213 a and 213 b is reflected.Therefore, due to the inner faces of the first and second holdingportions 2161 a and 2161 b, light loss by reflection inside the firstand second light-guiding members 213 a and 213 b can be respectivelysuppressed, thereby making it possible to increase the amount ofirradiation light onto the light irradiation face of the document G fromthe light emitting face M by a corresponding amount.

Furthermore, in the light source unit 210, the first and secondreflecting members 215 a and 215 b are provided at the first and secondholding portions 2161 a and 2161 b and the inner faces of the first andsecond tilted portions 2162 a and 2162 b, respectively. Consequently,due to the first and second reflecting members 215 a and 215 brespectively provided at the inner faces of the first and second holdingportions 2161 a and 2161 b, light loss by reflection inside the firstand second light-guiding members 213 a and 213 b can be suppressed. Inaddition, due to the first and second reflecting members 215 a and 215 brespectively provided in the inner faces of the first and second tiltedportions 2162 a and 2162 b, light loss by reflection of light emittedfrom the light emitting face M can be suppressed, thereby increasing theamount of irradiation light onto the light irradiation face of thedocument G from the light emitting face M by a corresponding amount.

Furthermore, the first and second holding portions 2161 a and 2161 brespectively hold the first and second light-guiding members 213 a and213 b while the first and second light-guiding members 213 a and 213 b,respectively, are in close contact to the inner faces thereof, therebysuppressing light leak in the light-guiding members 213 a and 213 b. Inthis manner, light loss by reflection inside the light-guiding members213 a and 213 b can be suppressed.

Furthermore, in the quadrangular first and second holding portions 2161a and 2161 b with one open side when viewed from the side, the length αin the width directions Xa and Xb at the open end is shorter than thelength β in the width directions Xa and Xb at the base end, and furtheris shorter than the length γ in the width directions Xa and Xb of thefirst and second light-guiding members 213 a and 213 b. In this manner,a force can be applied in the direction of the arrows in FIG. 10(a), andthus the first and second light-guiding members 213 a and 213 b can bereliably held on the open sides of the first and second holding portions2161 a and 2161 b, respectively. Accordingly, the first and secondlight-guiding members 213 a and 213 b and the first and second holdingportions 2161 a and 2161 b are in closer contact, respectively, therebysuppressing light leak in the light-guiding members 213 a and 213 b to acorresponding extent. As a result, light loss inside the light-guidingmembers 213 a and 213 b can be further suppressed.

Since the first and second holding portions 2161 a and 2161 b are eachformed by a metal material having elasticity, the first and secondlight-guiding members 213 a and 213 b and the first and second holdingportions 2161 a and 2161 b are in closer contact, respectively. Inaddition, since the first and second holding portions 2161 a and 2161 belastically deform when the first and second light-guiding members 213 aand 213 b are respectively fitted thereto, even though the light-guidingmembers 213 a and 213 b are repeatedly replaced, it is possible toreliably hold the light-guiding members 213 a and 213 b for a longperiod of time.

Note that at least one of the first light source portions 211 a 1 and211 a 2, or at least one of the second light source portions 211 b 1 and211 b 2 may be formed as a light source group configured from two ormore light sources (for example, LED elements).

In the present embodiment, as shown in FIGS. 4, 5 and 8, a reflectingmember 2181 is interposed on one side between the light source substrate2121 and the first and second light-guiding members 213 a and 213 b, anda reflecting member 2182 is interposed on the other side between theother light source substrate 2122 and the first and second light-guidingmembers 213 a and 213 b.

Specifically, the reflecting member 2181 on the one side is attached tothe fixing portion 2141 on the one side with one end portion of thesupporting plate 214 d in the longitudinal direction Y mounted thereto,and the light source substrate 2121 on the one side is arranged on theoutside thereof. Also, the reflecting member 2182 on the other side isattached to the fixing portion 2142 on the other side with the other endportion of the supporting plate 214 d in the longitudinal direction Ymounted thereto, and the light source substrate 2122 on the other sideis arranged on the outer side thereof.

In the present embodiment, the light source unit 210 further includes aradiator member 2191 on one side and a radiator member 2192 on the otherside. The radiator member 2191 on the one side is arranged so as tosurround the reflecting member 2181 on the one side and the light sourcesubstrate 2121 on the one side while being in close contact to thereflecting member 2181 on the one side. The radiator member 2192 on theother side is arranged so as to surround the reflecting member 2182 onthe other side and the light source substrate 2122 on the other sidewhile being in close contact to the reflecting member 2182 on the otherside.

Specifically, the radiator member 2191 on the one side closely contactsthe two side faces in the width direction of the reflecting member 2181on the one side and is attached to a frame body 210 x of the lightsource unit 210 so as to cover the back face of the one light sourcesubstrate 2121. Also, the radiator member 2192 on the other side closelycontacts the two side faces in the width direction of the reflectingmember 2182 on the other side and is attached to the frame body 210 x ofthe light source unit 210 so as to cover the back face of the lightsource substrate 2122 on the other side.

The reflecting members 2181 and 2182 and the radiator members 2191 and2192 are, here, each formed of a metal material such as aluminum. Notethat the reflecting member 2181 on the one side is provided with athrough hole T1 for allowing light from the first and second lightsource portions 211 a 1 and 211 b 1 on the one side to pass and thereflecting member 2182 on the other side is provided with a through holeT2 for allowing light from the first and second light source portions211 a 2 and 211 b 2 on the other side to pass.

With such a configuration, the reflecting face of the first and secondlight-guiding members 213 a and 213 b on the side of the end faces 213 a1 and 2131 b on the one side in the longitudinal direction Y can be thereflecting face of the reflecting member 2181 on the one side.Accordingly, light (particularly, on optical axes La2 and Lb2) guidedinto the light-guiding members 213 a and 213 b from the first and secondlight source portions 211 a 2 and 211 b 2 on the other side via theother end faces 213 a 2 and 213 b 2 in the longitudinal direction Y ofthe first and second light-guiding members 213 a and 213 b,respectively, is reflected by the reflecting face of the reflectingmember 2181 on the one side, thereby further improving reflectionefficiency. Also, the reflecting faces of the first and secondlight-guiding members 213 a and 213 b on the side of the end faces 213 a2 and 213 b 2 on the other side in the longitudinal direction Y can bethe reflecting face of the reflecting member 2182 on the other side.Accordingly, light (particularly, on optical axes La1 and Lb1) guidedinto the light-guiding members 213 a and 213 b from the first and secondlight source portions 211 a 1 and 211 b 1 on the one side via the endfaces 213 a 1 and 213 b 1 on the one side in the longitudinal directionY of the first and second light-guiding members 213 a and 213 b,respectively, is reflected by the reflecting face of the reflectingmember 2182 on the other side, thereby further improving reflectionefficiency. Therefore, reflection loss occurring when the optical axesLa1 and Lb1 of the first and second light source portions 211 a 1 and211 b 1 on the one side and the optical axes La2 and Lb2 of the firstand second light source portions 211 a 2 and 211 b 2 on the other sideare reflected inside the light-guiding members 213 a and 213 b can befurther suppressed. The amount of light irradiated onto the lightirradiation face of the document G from the light emitting face M can beincreased in accordance with the suppressed reflection loss.

Furthermore, with this configuration, the reflecting member 2181 on theone side and the reflecting member 2182 on the other side are eachformed by a metal material having a high thermal conductivity, andtherefore heat generated by the first and second light source portions211 a 1 and 211 b 1 on the one side and the first and second lightsource portions 211 a 2 and 211 b 2 on the other side can be effectivelyreleased by the reflecting members 2181 and 2182.

Furthermore, with the present embodiment, since the radiator member 2191on the one side provided in close contact to the one reflecting member2181 surrounds the reflecting member 2181 on the one side and the lightsource substrate 2121 on the one side, heat generated in the first andsecond light source portions 211 a 1 and 211 b 1 on the one side can bereleased directly and indirectly via the reflecting member 2181 on theone side. Also, since the radiator member 2192 on the other sideprovided in close contact to the reflecting member 2182 on the otherside surrounds the reflecting member 2182 on the other side and thelight source substrate 2122 on the other side, heat generated in thefirst and second light source portions 211 a 2 and 211 b 2 on the otherside can be released directly and indirectly via the reflecting member2182 on the other side. Note that the reflecting members 2181 and 2182may be configured from a reflection film, a member that supports thereflection film and has a high thermal conductivity such as a metalmember.

DESCRIPTION OF REFERENCE NUMERALS

-   100 Image reading apparatus-   210 Light source unit (example of illuminating device)-   211 a 1, 211 b 1 First and second light source portions on one side-   211 a 2, 211 b 2 First and second light source portions on the other    side-   213 a, 213 b First and second light-guiding members-   215 a, 215 b First and second reflecting members-   216 a, 216 b First and second holding members-   2161 a, 2161 b First and second holding portions-   2162 a, 2162 b First and second tilted portions-   D: Image forming apparatus-   G: Original as illumination target-   M: Light emitting face-   Xa, Xb: Width direction-   Y: Longitudinal direction-   α: Width-direction length at open end of holding portion having    sideway U-shape-   β: Width-direction length at base end of holding portion having    sideway U-shape-   γ: Width-direction length of light-guiding member

1. An illuminating device comprising: a light-emitting element; asubstrate on which the light-emitting element is mounted; and alight-guiding member which guides light from the light-emitting elementvia an end portion of the light-guiding member in a longitudinaldirection and thereby illuminates an illumination target from a lightemitting face that extends in the longitudinal direction of thelight-guiding member, wherein the illuminating device includes aradiator member disposed so as to face the substrate, wherein theradiator member is made of a metal material, wherein the radiator memberis connected to the substrate, and wherein the radiator member isconnected to a metal member that is a component of the illuminatingdevice.
 2. The illuminating device according to claim 1, wherein theradiator member and the metal member are connected to each other so asto have a heat conduction path formed by metallic contact.
 3. Theilluminating device according to claim 1, wherein the substrate and theradiator member are connected to each other so as to have a heatconduction path formed by contact between members.
 4. The illuminatingdevice according to claim 1, wherein the radiator member is arranged incontact with the substrate.
 5. The illuminating device according toclaim 1, wherein the radiator member includes: a first radiator memberarranged so as to face a light-emitting element-mounted surface of thesubstrate; and a second radiator member arranged so as to face anopposite surface of the light-emitting element-mounted surface.
 6. Theilluminating device according to claim 5, wherein the first radiatormember and the second radiator member are arranged in contact with eachother.
 7. The illuminating device according to claim 5, wherein at leastone of the first radiator member and the second radiator member isconnected to the substrate, and wherein at least one of the firstradiator member and the second radiator member is connected to the metalmember that is a component of the illumination device.
 8. Theilluminating device according to claim 5, wherein the metal member isthe first radiator member or the second radiator member.
 9. Theilluminating device according to claim 5, wherein the metal member is atleast one member that is a component of a light source light-guidingunit that is configured by the light-guiding member, the first radiatormember, the second radiator member and the light-emitting element. 10.The illuminating device according to claim 5, wherein the metal memberis a base to which a light source light-guiding unit is attached, thelight source light-guiding unit being configured by the light-guidingmember, the first radiator member, the second radiator member and thelight-emitting element.
 11. The illuminating device according to claim5, wherein the metal member is a base to which at least the firstradiator member, the second radiator member and the substrate areattached.
 12. The illuminating device according to claim 5, wherein thefirst radiator member is provided with a through hole for passing thelight from the light-emitting element to the end portion of thelight-guiding member.
 13. The illuminating device according to claim 1,wherein a connector is provided on a light-emitting element-mountedsurface of the substrate.
 14. The illuminating device according to claim5, wherein at least one of the first radiator member and the secondradiator member is formed of aluminum.
 15. The illuminating deviceaccording to claim 5, wherein the first radiator member is arranged incontact with the end portion of the light-guiding member in thelongitudinal direction.
 16. The illuminating device according to claim5, wherein the first radiator member and the second radiator member arefixed to each other by a fastening member in such a manner as to holdthe substrate therebetween.
 17. The illuminating device according toclaim 1, wherein the light-guiding member is held by a holding membermade of a metal material.
 18. The illuminating device according to claim5, wherein the first radiator member includes a reflecting member forreflecting the light from the light-emitting element.
 19. An imagereading apparatus comprising the illuminating device according toclaim
 1. 20. An image forming apparatus comprising the image readingdevice according to claim
 19. 21. An illuminating device comprising: alight-emitting element; a substrate on which the light-emitting elementis mounted; and a light-guiding member which guides light from thelight-emitting element via an end portion of the light-guiding member ina longitudinal direction and thereby illuminates an illumination targetfrom a light emitting face that extends in the longitudinal direction ofthe light-guiding member, wherein the illuminating device includes: afirst radiator member arranged so as to face a light-emittingelement-mounted surface of the substrate; and a second radiator memberarranged so as to face an opposite surface of the light-emittingelement-mounted surface, wherein at least one of the first radiatormember and the second radiator member is connected to the substrate,wherein the first radiator member and the second radiator member areeach made of a metal material, wherein the first radiator member and thesecond radiator member are connected to each other so as to have a heatconduction path formed by contact of metal members, and wherein thefirst radiator member is provided with a through hole for passing thelight from the light-emitting element to the end portion of thelight-guiding member.
 22. The illuminating device according to claim 21,wherein the first radiator member and the second radiator member arearranged in contact with each other.
 23. The illuminating deviceaccording to claim 21, wherein the second radiator member is arranged incontact with the substrate.
 24. The illuminating device according toclaim 21, further comprising: a light source light-guiding unit that isconfigured by the light-guiding member, the first radiator member, thesecond radiator member and the light-emitting element; and a base towhich the light source light-guiding unit is attached, wherein at leastone of the first radiator member and the second radiator member servesas an attachment member for attaching the light source light-guidingunit to the base.
 25. The illuminating device according to claim 21,wherein a connector is provided on the light-emitting element-mountedsurface of the substrate.
 26. The illuminating device according to claim21, wherein at least one of the first radiator member and the secondradiator member is formed of aluminum.
 27. The illuminating deviceaccording to claim 21, wherein the first radiator member is arranged incontact with the end portion of the light-guiding member in thelongitudinal direction.
 28. The illuminating device according to claim21, wherein the first radiator member and the second radiator member arefixed to each other by a fastening member in such a manner as to holdthe substrate therebetween.
 29. The illuminating device according toclaim 21, wherein the light-guiding member is held by a holding membermade of a metal material.
 30. The illuminating device according to claim21, wherein the first radiator member includes a reflecting member forreflecting the light from the light-emitting element.
 31. An imagereading apparatus comprising the illuminating device according to claim21.
 32. An image forming apparatus comprising the image reading deviceaccording to claim 31.